Synthesis, Characterization, and Antimicrobial Activity of Salisaldehyde-Based Terpolymeric Ligand and Its Transition Metal Complexes

Abstract

In this study, we first synthesized a salisaldehyde-based terpolymer (SBT) ligand using salisaldehyde and phenylthiourea with glutaraldehyde. We then synthesized SBT metal complexes (SBT-M(II)) with the use of transition metal ions, such as Co(II), Ni(II), Cu(II), and Zn(II). To elucidate the structure and geometry of the metal ions, SBT and SBT-M(II) were characterized by elemental and spectral analysis. SBT-Co(II) and SBT-Ni(II) showed six coordination bonds with two water molecules, whereas SBT-Cu(II) and SBT-Zn(II) showed four coordination bonds. Gel permeation chromatography was used to determine the molecular weight of SBT. The thermal stability of SBT and SBT-M(II) was tested using thermogravimetric and differential thermal analysis. Thermal kinetic parameters such as activation energy and exponential factor were calculated using the Coats–Redfern method. In addition, antibacterial activity of SBT and SBT-M(II) was evaluated against several bacterial and fungal cultures using the agar well diffusion method. The polarity of the metal ion in SBT-M(II) was reduced which might contribute to its superior antimicrobial property.